Mark Wilson August 1st, 2012
WOOSTER, OHIO–One of the best parts of my job is answering questions from the public about rocks and fossils. Now that I’m Secretary of the Paleontological Society, I get queries every day about something or other. (And since my brief stint on Ancient Aliens, some of my mail is predictably bizarre!) Sometimes the questions are local and students and I get to meet enthusiastic amateur geologists in the field. This morning Andy Nash (’14) and I drove a few miles north of Wooster to look at curious rocks a family had collected, and to walk through their stone-filled creek. It was delightful.
This part of Ohio has many exotic rocks scattered across its surface in Pleistocene glacial till. These rocks have their origin on the Canadian Shield and include just about every igneous and metamorphic lithology you can imagine. The family we visited had many examples of these glacial erratics. The most impressive rocks to Andy and me were pieces of the Gowganda Tillite, one of which is shown above. This rock represents lithified glacial till and is a very impressive 2.3 billion (billion-with-a-“b”) years old. This great age, plus the fact that it is a tillite within a till, makes these variegated rocks very special. The family is going to donate this one to the department, even though it will take a tractor to haul it out!
Another bonus for our brief visit was this creek exposure of the Meadville Shale Member of the Cuyahoga Formation (Kinderhookian, Carboniferous). An outcrop like this so close to campus will be useful for future paleontology field trips and maybe even an Independent Study project or two. The family that owns the land is very excited to share it. (By the way, my first paper was on a trilobite collected from the Meadville Shale in Lodi, Ohio.)
The shale outcrop is periodically broken up by floods on this little creek. Here you see scattered pieces of the gray shale, many of which have trace and body fossils in them. This shale weathers rapidly, exposing the fossils quickly. The downside of that is that the fossils are also destroyed quickly by weathering. They need the kind attention of paleontologists!
This is why we love to answer questions about geology: everyone learns in the process!